The patterning of radiation sensitive polymeric films with actinic radiation such as ultraviolet light at wavelengths of 436, 365, 257, 248, 193 or 157 nanometers (nm) is the principle means of defining high resolution circuitry found in semiconductor devices. The radiation sensitive films, often referred to as photoresists, generally consist of multi-component formulations that are coated onto a desired substrate. The radiation is exposed patternwise and induces a chemical transformation that renders the solubility of the exposed regions of the films different from that of the unexposed areas when the films are treated with an appropriate developer.
Chemically amplified photoresists are based on a catalytic mechanism that allows a relatively large number of chemical events such as, for example, de-protection reactions in the case of positive photoresists or cross-linking reactions in the case of negative tone photoresists, to be brought about by the application of a relatively low dose of radiation that induces formation of a catalyst, often a strong acid. However, chemically amplified photoresists, particularly in the sub-50 nm regime, experience diminished image resolution or contrast, often referred to as “image blur.”
Therefore, there is an ongoing need for new photoresist compositions having improved image resolution capability as well as improved methods of patterning substrates.